Request: Document "--pid-file" parameter

[Maddes]

Hello authors and contributors,

I'm missing a paragraph about svnserve's "--pid-file <filepath>"
parameter in the book.

When the parameter is used, then svnserve writes its own process id into
the given file.
The user under which svnserve runs must be allowed to write to the given
location.

The parameter works correctly on Unix/Linux and Windows.
I tested on Debian 4.0 and on XP SP2 with Subversion 1.4.

It's a useful parameter when implementing Subversion into the System V
Init system.
I wrote myself a Debian init script for Subversion (available at
http://www.maddes.net/freeware/debian.htm#subversion)
As I used an extra user for Subversion (not root) I had to create a
svnserve folder in /var/run and set its owner to the svnserve user.

Regards
Matthias "Maddes" Bücher